The present invention relates to vehicle control methods and more particularly to an efficiency-based vehicle control method.
Conventional internal combustion engines include a limited number of control inputs. Among the various control inputs, there are three main inputs: ignition angle, fuel flow rate (fuel mass) and airflow rate. For a traditional cable throttle vehicle, a driver""s input translates to a desired airflow rate, leaving ignition angle and fuel flow rate as control variables. Given the airflow rate, an xe2x80x9coptimizedxe2x80x9d ignition angle and fuel flow rate may be determined as a function of the best power, best emissions, and best fuel economy or as a compromise therebetween.
There is an increasing need within the automotive industry for simultaneous improvements in the areas of vehicle performance, improved emissions and fuel economy. In pursuit of these goals, increasingly complex technical solutions for optimizing vehicle and powertrain performance have been implemented. As a result of these technical solutions many actuation mechanisms have been introduced for providing a performance control means. Among many others, these actuators may include: electronic throttle control, variable valve timing, cylinder deactivation, direct injection, continuously variable transmission and the like. In order to realize the maximum benefit of these actuators, improved interfaces between the various vehicle systems need be developed.
As the amount and variety of these actuators increase, choosing the optimal positioning of each at any given instant becomes an increasingly complex task. Commonly, non-unique actuator position solutions are available for a given xe2x80x9coptimization goalxe2x80x9d. The difficulty in determining the desired actuator position is compounded, as there are no standard actuator configurations. In other words, different vehicle types and powertrain layouts implement different types and numbers of actuators. Thus, each vehicle layout requires respective control and calibration strategies.
Therefore, it is desirable in the industry to develop a generic control method that will determine and assign optimal actuator positions. The actuator position determination should be a function of a given optimization goal, the particular vehicle system configuration and the particular constraints of the vehicle system configuration. The generic control method should be flexible for future consideration of powertrain configurations, such as simple internal combustion engines with stepped transmissions or advanced powertrains such as electric hybrids and fuel cell powered vehicles.
Accordingly, the present invention provides a vehicle including a powertrain having a power unit, an actuator associated with the power unit for selectively manipulating operation of the power unit, a sensor for sensing operational performance of the power unit and an efficiency controller in communication with the actuator and the sensor. The controller performs the method of the present invention, whereby the controller receives present operational data and efficiency data from the sensor for determining an optimized operation mode of the power unit and accordingly actuates the actuator for operating the power unit in the optimized operation mode.
The present invention provides a method of controlling a vehicle system having a power unit. The method includes the steps of: determining an efficiency of the power unit, determining present operational data of the power unit, determining a torque to be provided to the vehicle system, determining a plurality of optimization constraints as a function of the torque to be provided, the present operational data and the efficiency of the power unit, determining an optimized operation mode of the power unit as a function of the optimization constraints and the present operational data of the power unit, and manipulating the power unit to operate in the optimized operation mode.
The efficiency-based control method of the present invention addresses the needs described hereinabove. Essentially, all vehicle system components are characterized in terms of their respective efficiencies, thereby enabling the control method to be generic, and are then related to an overall vehicle system efficiency.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.